KR100194564B1 - Organic composite plated steel sheet and resin composition for coatings used therein - Google Patents

Abstract

The present invention relates to an organic composite plated steel sheet obtained by applying a thermosetting resin to a chromate-coated alloy plated steel sheet and curing it, wherein the thermosetting resin is, for example, a water-soluble vinyl-modified epoxy ester resin and a water-soluble vinyl-modified epoxy ester resin. Improved organic composite plating comprising using various water-soluble resin compositions of the type consisting of a system consisting of a block isocyanate compound or a system consisting of a water-soluble vinyl modified epoxy ester resin and a block isocyanate compound / coidal silica. Steel plate. According to the present invention, it is particularly excellent in adhesiveness with adhesives, continuous welding, corrosion resistance and electrodeposition coating property after processing, and also excellent in paint adhesion and corrosion resistance, and especially in the sensibility (smoothness) of the painted surface after electrodeposition coating, In addition, it is possible to provide a novel and highly practical organic composite plated steel sheet of a type in which a water-soluble resin (composition) for organic composite coating, which is excellent in corrosiveness and does not use a large amount of organic solvent, is precoated with a metal material.

Description

[Name of invention]

Organic composite plated steel sheet and resin composition for coatings used therein

Detailed description of the invention

[Technical Field]

The present invention relates to a novel and useful organic composite plated steel sheet and a resin composition for coating used in the coating thereof. More specifically, the present invention can be obtained by applying and curing a specific organic resin or a composition containing a specific organic resin on a specific chromate coated plated steel sheet, and in particular, adhesion to an adhesive, continuous welding, corrosion resistance after processing, and electrodeposition coating property. The present invention relates to an organic composite plated steel sheet excellent in high corrosion resistance and paint adhesion, and a resin composition for paint.

In addition, it has been found that mixing a blocked isocyanate compound, which is a curing agent, to a specific organic resin at a molecular level provides an organic composite plated steel sheet having excellent corrosion resistance, in particular, and the present invention is to provide an organic composite plated steel sheet of this specific type. It is.

Background Technology

Recently, due to the explosion of organic solvents in the paint, air pollution, labor safety and hygiene problems, the conversion from organic solvent paints to water based paints has been rushing.

However, in the automobile, rigid furniture, or household electrical appliance industry, the adoption of pre-coated metal materials is increasing to improve productivity.

In order to meet such demands in the field of surface coating paints, various coating compositions for pre-coated metal materials have been developed, but also in this field, there is an rush to change from conventional organic solvent paints to water based paints.

Moreover, in the system using conventional organic solvent type paint, for example, in order to secure the electroconductivity which becomes an essential condition for securing electrodeposition coating property, For example, Unexamined-Japanese-Patent No. 45-2430 or 4-6882 The invention described in the publication and the like proposes a zinc enriched paint. Such zinc-enriched paints are only capable of electrodeposition coating, but the smoothness of the arrival surface is insufficient. In addition, in this zinc concentrate coating, the coating is unstable against corrosion due to corrosion progressing, and thus the corrosion resistance cannot be secured over a long period of time (corrosion resistance cannot be secured). Moreover, the coating is likely to be destroyed after processing. It also has the drawback of falling.

On the other hand, the invention described in Japanese Patent Application Laid-Open No. 52-44569, Japanese Patent Application Laid-Open No. 58-19706, Japanese Patent Application Laid-Open No. 51-79138, or Japanese Patent Application Laid-open No. 58-138758 is intended to enable electrodeposition coating. There is proposed a paint in which a conductive pigment is blended.

However, in such a paint material, particles having a relatively large particle diameter of an average particle diameter of 1 micron or more, such as metal powder such as zinc, metal carbide powder or metal phosphide powder, are used as the conductive pigment. Therefore, in the coating film formed, unevenness or a flaw due to the conductive material added during press working adheres to the surface of the steel sheet, or unevenness or flaw remains on the electrodeposition coating surface, and as a result, two or three coating coatings are formed. There is a problem that such irregularities or flaws remain on the surface of the coating film as it is, or there is a drawback that corrosion resistance can not be secured accordingly.

In addition, Japanese Unexamined Patent Publication No. 58-224174, 60-197778, 60-199074, 60-174879, etc. disclose an organic composite silicate coating film and its coated steel sheet. It is. This organic silicate film does not contain a conductive pigment and is a very thin film of 0.2 to 5.0 microns (µm). However, the organic silicate film has high corrosion resistance due to the bonding of an organic binder and colloidal silica, and among them, a marked improvement in press workability and the like is seen.

However, there is a problem of irregularities on the electrodeposition coating, and in particular, there is a problem that the film thickness of the electrodeposition coating film formed thereon also varies greatly in response to the variation in the film thickness of the organic composite silicate coating film. That is, there was a problem that the electrodeposition coating film was thick at the site where the film thickness of the organic composite silicate coating film was thick, and the electrodeposition coating film was thin at the site where the thickness of the organic composite silicate coating was thin, and the irregularities were further expanded by the electrodeposition coating film. In addition, organic composite silicate coatings tend to have low corrosion resistance.

In addition, according to the method disclosed in Japanese Patent Laid-Open No. 62-283161 or Japanese Patent Laid-Open No. Hei 3-269067, the above problems are solved considerably, but there are complaints. That is, these methods require the use of a special organic solvent or the use of special additives, and have the disadvantage of poor adhesion with an adhesive such as vinyl chloride sol, and the like, and there is no glossiness of the electrodeposition coating film, that is, high brightness and smoothness. It is also insufficient. In addition, it is necessary to dilute with a large amount of organic solvents, since it is necessary to dilute sufficiently with the coating material used in the need to coat a coating film very thinly.

However, the present inventors have diligently researched in order to obtain a novel and highly practical organic composite plated steel sheet having no such defects or defects in view of such defects or defects in the prior art.

That is, the present invention is excellent in adhesiveness with the adhesive, continuous welding, corrosion resistance and electrodeposition coating after processing, and also excellent in paint adhesion and corrosion resistance, and also excellent in the sensibility (smoothness) of drawings after electrodeposition coating, and also An object of the present invention is to provide a novel and highly practical organic composite plated steel sheet in which a water-soluble resin for coating an organic composite, which is excellent in corrosiveness and does not use a large amount of organic solvent, is precoated in a metal material.

[Initiation of invention]

The improved organic composite plated steel sheet according to claim 1 of the present invention is an organic composite plated steel sheet obtained by applying and curing a thermosetting resin to a chromate coated alloy plated steel sheet, wherein the above-mentioned thermosetting resin is composed of an aromatic epoxy resin and a fatty acid. The epoxy ester resin obtained by the reaction is modified by the addition reaction of a vinyl monomer having a carboxyl group-containing ethylenic vinyl monomer as an essential component, and the water-soluble vinyl-modified epoxy ester resin obtained by neutralization with a basic compound is included as an essential film forming component. A water soluble resin composition is used.

In addition, the improved organic composite plated steel sheet according to claim 2 of the present invention is an organic composite plated steel sheet obtained by coating and curing a thermosetting resin on a chromate-coated alloy plated steel sheet, wherein the aromatic epoxy resin as the thermosetting resin. A water-soluble vinyl-modified epoxy ester resin obtained by modifying an epoxy ester resin obtained by the reaction of a fatty acid with a vinyl monomer containing a carboxyl group-containing ethylenic vinyl monomer as an essential component and neutralizing it with a basic compound, and a curing agent thereof. A water soluble resin composition is used.

In addition, the improved organic composite plated steel sheet according to claim 3 of the present invention is an organic composite plated steel sheet obtained by applying a thermosetting resin to a chromate-coated alloy plated steel sheet and curing the aromatic composite resin as an aromatic epoxy resin. A water-soluble vinyl-modified epoxy ester resin obtained by modifying an epoxy ester resin obtained by the reaction of a fatty acid with a vinyl monomer having a carboxyl group-containing ethylenic vinyl monomer as an essential component and neutralizing with a basic compound, SiO ₂ , Cr _A water-soluble resin composition composed of one or two or more powders or colloids of ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, ZrO ₂ , SnO ₂ , Al ₂ O _3, or Sb ₂ O ₅ use.

In addition, the improved organic composite plated steel sheet according to claim 4 of the present invention is an organic composite plated steel sheet obtained by applying and curing a thermosetting resin on a chromate-coated alloy plated steel sheet, wherein the aromatic epoxy resin as the thermosetting resin. A water-soluble vinyl-modified epoxy ester resin obtained by modifying an epoxy ester resin obtained by the reaction of a fatty acid with a vinyl monomer having a carboxyl group-containing ethylenic vinyl monomer as an essential component and neutralizing it with a basic compound, a curing agent thereof, Consisting of one or two or more powders or colloids of SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, ZrO ₂ , SnO ₂ , Al ₂ O ₃ or Sb ₂ O ₅ A water soluble resin composition is used.

The improved organic composite plated steel sheet according to claims 1 to 4 is particularly excellent in adhesion with adhesives, continuous welding, corrosion resistance and electrodeposition coating properties after processing, and also excellent in paint adhesion and corrosion resistance. After painting, the sensibility (smoothness) of the drawing is excellent.

In addition, when the water-soluble vinyl-modified epoxy ester resin and the curing agent are used instead of the blocked isocyanate compound and the water-soluble resin composition in which the vinyl-modified epoxy ester resin is uniformly mixed at the molecular level, an advantage in that the corrosion resistance is particularly excellent can be obtained. have.

Best Mode for Carrying Out the Invention

Therefore, the present inventors have focused on the problem to be solved by the above-described inventions, and have intensively studied. As a result, the present invention has been completed.

That is, the present invention is basically each,

(1) A water-soluble vinyl-modified epoxy ester resin obtained by modifying an epoxy ester resin obtained by the reaction of an aromatic epoxy resin with a fatty acid by addition reaction of a vinyl monomer having a carboxyl group-containing ethylenic vinyl monomer as an essential component and neutralizing it with a basic compound. An improved organic composite chromate-coated alloy plated steel sheet consisting of using a water-soluble resin composition containing as an essential film forming component;

(2) A water-soluble vinyl-modified epoxy ester resin obtained by modifying an epoxy ester resin obtained by the reaction of an aromatic epoxy resin with a fatty acid by addition reaction of a vinyl monomer having a carboxyl group-containing ethylenic vinyl monomer as an essential component and neutralizing it with a basic compound. And an improved organic composite chromate-coated alloy plated steel sheet composed of using a water-soluble resin composition comprising the curing agent;

(3) A water-soluble vinyl-modified epoxy ester resin obtained by modifying an epoxy ester resin obtained by the reaction of an aromatic epoxy resin with a fatty acid by addition reaction of a vinyl monomer having a carboxyl group-containing ethylenic vinyl monomer as an essential component and neutralizing it with a basic compound. And one or two or more kinds of powder or colloid (sol) of SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, ZrO ₂ , SnO ₂ , Al ₂ O ₃ or Sb ₂ O ₅ ; An improved organic composite chromate-coated alloy plated steel sheet consisting of using a water-soluble resin composition comprising;

(4) A water-soluble vinyl-modified epoxy ester resin obtained by modifying an epoxy ester resin obtained by the reaction of an aromatic epoxy resin with a fatty acid by addition reaction of a vinyl monomer having a carboxyl group-containing ethylenic vinyl monomer as an essential component and neutralizing it with a basic compound. And a curing agent and one of powder or colloid (sol) of SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, ZrO ₂ , SnO ₂ , Al ₂ O _3, or Sb ₂ O ₅ ; Or to provide an improved organic composite chromate-coated alloy plated steel sheet consisting of using a water-soluble resin composition consisting of two or more kinds, and the epoxy ester resin obtained by the reaction of the aromatic epoxy resin and fatty acid carboxyl group-containing ethylenic vinyl Denatured by addition reaction of vinyl monomer containing monomer as an essential component and neutralized with basic compound It is of the aqueous vinyl-modified epoxy ester resin _{(A-1), SiO 2} , Cr 2 O 3, Fe 2 O 3, Fe 3 O 4, MgO, ZrO 2, SnO 2, Al 2 O 3 or Sb ₂ O ₅ A resin composition for coating for a chromate-coated alloy plated steel sheet comprising one or two or more kinds of powder or colloid (sol) (B), a curing agent (C) and, if necessary, pigments (D);

In addition, the vinyl-modified epoxy ester resin and the blocked isocyanate compound modified by the addition reaction of a vinyl monomer having an carboxyl group-containing ethylenic vinyl monomer as an essential component by the reaction of an aromatic epoxy resin with a fatty acid at a molecular level. A water-soluble vinyl-modified epoxy ester resin (A-2) containing a blocked isocyanate compound obtained by mixing uniformly and water-soluble, and SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, ZrO ₂ , SnO ₂ , Al ₂ O ₃ or Sb ₂ O ₅ or one or two or more kinds of powder or colloid (sol) (B), a curing agent (C) if necessary, and pigments (D) if necessary To provide a resin composition for coating for chromate-coated alloy plated steel sheet.

(5) The present invention specifically relates to a specific resin composition in which a water-soluble vinyl-modified epoxy ester resin and a curing agent thereof are obtained by homogeneously mixing and water-solubilizing a vinyl-modified epoxy ester resin and a blocked isocyanate compound at a molecular level. The present invention also provides an improved organic composite chromate-coated alloy plated steel sheet.

The present invention also provides an organic composite plated steel sheet having an organic coating amount of 0.2 to 3.0 g / m ² obtained by applying and curing various water-soluble resin compositions such as (1) to (5).

The chromate-coated alloy plated steel sheet used in the present invention is a plated steel sheet of various single element (metallic materials) such as Zn, Ni, Cu, Sn, Co or Al, or Zn-Ni-based alloy plated, Zn- Fe-based alloy plating, Zn-Cr alloy plating, Zn-Cu alloy plating, Zn-Mn alloy plating, Zn-Al alloy plating, Zn-Mg alloy plating, or Zn-Cr-Nifl alloy plating It refers to a steel sheet in which a chromate coating is formed on various alloy plated steel sheets.

Among these platings, Zn or Sn plating or Zn-based alloy plating is preferable, and Zn or Zn-based alloy plating is preferable.

Here, a chromate film refers to the chromium passivation layer which is a composite containing a trivalent and hexavalent chromium hydroxide of the form obtained by apply | coating electrolytic chromate, application | coating chromate, or reactive chromate etc., and drying and hardening | curing. will be.

The chromium deposition amount of the chromate coating is preferably in the range of 10 to 150 mg / m ² . If quality chromium coating weight is 10mg / m Case ² is less than all means the adhesion is easy to not be able to form an excellent organic coating, and also because there is a tendency that the corrosion resistance is lowered, while too large in excess of 150mg / m ^2, the chromate film This is because there is a tendency to cause a cohesive film, and in particular, to reduce the paint adhesion and the like.

The present invention can be carried out by applying and curing a water-soluble resin composition containing a water-soluble vinyl-modified epoxy ester resin having a specific composition as an essential film-forming component to the chromate-coated alloy plated steel sheet as described below.

Such water-soluble vinyl-modified epoxy ester resin refers to resin obtained by manufacturing as follows, for example.

That is, first, the aromatic epoxy resin and the fatty acid are esterified at about 150 to 250 ° C. for about 2 hours to about 10 hours while heating and stirring to dissolve it in a desired organic solvent, and vinyl having the carboxyl group-containing ethylenic vinyl monomer as an essential component. The monomer is added with a polymerization initiator to perform a graft reaction while heating and stirring at about 50 ° C. to about 150 ° C. to obtain a vinyl-modified epoxy ester resin.

Subsequently, the carboxyl group in the vinyl-modified epoxy ester resin thus obtained is thickened as a basic compound and then obtained by dispersing in water.

Specific examples of the aromatic epoxy resins used herein include bisphenol A epoxy resins, bisphenol F epoxy resins, and novolac epoxy resins.

The number average molecular weight of these aromatic epoxy resins needs to be in the range of approximately 800 to 6,000. If the number average molecular weight is less than 800, the corrosion resistance may be lowered. On the other hand, if the number average molecular weight is higher than 6,000, it may be difficult to use because it is likely to become high viscosity during the synthesis of the resin.

Particularly representative examples of commercially available products of the aromatic epoxy resins include "Epicoat 152, 154, 1001, 1002, 1004, 1007, 1009 or 1010" (brand name) manufactured by Dutch Shell Corporation; Or "Epicron 1050, 1055, 4050, 3050, 7050 or 9055j (trade name), etc. of Dainippon Inkakugaku Kogyo Co., Ltd., and these may be used alone or in combination of two or more.

In the present invention, the aromatic epoxy resin is used as an essential component for maintaining corrosion resistance and maintaining adhesion with an adhesive such as a base material (base material) or an electrodeposition coating film or vinyl chloride sol.

The usage-amount of such an aromatic epoxy resin is suitable in the range of about 5 to 80 weight%. If the amount of use is less than 5% by weight, the above-mentioned effects are likely to be less likely. On the other hand, if the amount exceeds 80% by weight, the resin design becomes difficult. More preferably, it is suitable in the range of about 10 to 60% by weight in view of continuous weldability and the like.

Subsequently, the use of dry fatty acid is preferred as the fatty acid in order to secure the graft point in the subsequent so-called vinyl modification. When using an undried oil fatty acid, it is necessary to ensure the graft point and to react by adding small amount of various unsaturated dicarboxylic acids, such as maleic acid, fumaric acid, or itaconic acid.

Specific examples of the fatty acids that can be used include linseed oil fatty acid, soybean oil fatty acid, safflower oil fatty acid, rapeseed oil fatty acid, sesame oil fatty acid, coconut oil fatty acid, palm oil fatty acid, palm kernel oil fatty acid, rice oil fatty acid, castor oil fatty acid or dehydrated castor Milk fatty acids and the like. As the usage-amount of the said fatty acid, the sum total with the aromatic epoxy resin mentioned above becomes 100 weight% is suitable.

In the case of esterification reaction, various imidazoles represented by 2-methyl imidazole etc. as a reaction catalyst; Various tertiary amines represented by triethyl amine or dimethyl benzylamine; Or various basic substances, such as various quaternary amines represented by tetramethyl ammonium chloride, etc. may be added, and this esterification reaction may be performed under reflux of toluene, xylene, etc. in order to remove condensed water.

Specific examples of the organic solvents used for vinyl modification include various hydrophobic organic solvents such as toluene, xylene, minerals, and spirits; Various alcohol solvents such as methanol or ethanol or butanol;

Various ether solvents such as methyl ether, ethyl ether or tetrahydrofuran; Various ketone solvents represented by acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone; Various ethylene glycol solvents such as ethyl cellosolve, butyl cellosolve or cellosolve acetate; Various propylene glycol solvents such as propylene glycol monobutyl ether and the like; Known hydrophilic organics including various diethylene glycol-based solvents such as butyl carbitol and the like, and various solvents such as N-methyl-2-pyrrolidone, dimethyl formamide, dimethyl acetamide, and dimethyl sulfoxide and the like. The solvent can be used in any ratio.

Since hydrophobic organic solvents have poor dispersion stability (water dispersion stability) with respect to water, it is preferable to use a hydrophilic organic solvent. Moreover, although the usage-amount is not specifically limited, Usually, it is used in the range which resin solid content becomes about 5 to 80 weight%.

Examples of the polymerization initiator used in vinyl modification include, for example, various inorganic peroxide compounds represented by potassium persulfate, ammonium persulfate, hydrogen peroxide or percarbonate; Various ketone peroxides represented by methyl ethyl ketone peroxide and the like; Various peroxy ketols represented by 1,1-bis (tert-butyl peroxy) -3,3,5-trimethylcyclohexanone and the like; various hydroperoxides represented by tart-butylhydroperoxide and the like; Various diacyl peroxides represented by benzoyl peroxide and the like; Various dialkyl peroxides represented by di-tert-butyl peroxide and the like; Various peroxy dicarbonates represented by dioxy propyl peroxy dicarbonate and the like; various organic peroxide compounds including various peroxy esters such as tert-butyl peroxy-2-ethyl hexanate and the like; Or various azo compounds represented by azobis isobutylonitrile and the like.

Moreover, as a vinyl monomer to be used, a carboxyl group-containing ethylenic vinyl monomer must be used as an essential component in order to make it water-soluble in a subsequent process.

Or when using a hardening | curing agent together, in order to ensure sclerosis | hardenability enough, use of a hydroxyl-containing ethylenic vinyl monomer is also preferable.

Specific examples of the carboxyl group-containing ethylenic vinyl monomers include various unsaturated mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid or citraconic acid.

In addition, examples of hydroxyl group-containing ethylenic vinyl monomers, which are particularly representative, include 2-hydroxy ethyl methacrylate, 2-hydroxy ethyl acrylate, 2-hydroxy propyl methacrylate, 2-hydroxy propyl acrylate, and the like. to be. These are, of course, used alone or in combination of two or more.

In addition to each of these carboxyl group-containing ethylenic vinyl monomers and hydroxyl group-containing ethylenic vinyl monomers, if necessary, other ethylenic vinyl monomers polymerizable with both functional group-containing ethylenic vinyl monomers may be used.

Specific examples of ethylenic vinyl monomers that can be used include various (meth) acrylic acid alkyl esters such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate or lauryl (meth) acrylate. Ryu; Various α- to β-unsaturated amides such as acryl amide, methacryl amide or N-methyrol acryl amide; Various α- to β-unsaturated nitriles such as acrylonitrile or methacrylonitrile; Various styrene derivatives such as styrene, α-methylstyrene or vinyl toluene; Or various vinyl esters such as vinyl acetate, vinyl propionate or "Beover" (trade name; vinyl esters of branched aliphatic monocarboxylic acids from the Dutch Shell company), and also vinyl chloride or vinylidene chloride. Various vinyl halides such as external fluorine-containing monomers; Or various complex dienes such as butadiene.

These various monomers may be used alone or in combination of two or more. In addition, the polymerizable polyester resin, alkyd resin, etc. can also be used together.

As the usage-amount of each ethylenic vinyl monomer disclosed above, since it is suitable in the range of about 3-50 weight part with respect to 100 weight part of reaction products of the aromatic epoxy resin and aliphatic which were demonstrated previously, it is good to react at such a ratio.

The usage-amount of the carboxyl group-containing ethylenic vinyl monomer which is an essential component mentioned above here is suitable in the range of about 3-30 parts. If the amount of use is less than about 3 parts, the particle size of the finally obtained water-soluble dispersion tends to be large, and as a result, the sedimentation stability tends to be poor, making it difficult to put to practical use. This is because if neutralized with a basic compound, it will not become a water-soluble dispersion, but becomes water-soluble only. In this case, if the degree of neutralization is lowered, a water-soluble dispersion can be obtained, but in any case, since it tends to be dissolved by an alkaline substance, an organic film having poor alkali resistance and the like is particularly poor.

Specific examples of the basic compound used for neutralizing the carboxyl group in the resin when the reaction product is solubilized in an aqueous medium include ammonia, volatile amines, and the like, and the use of such volatile substances is preferable.

Incidentally, inorganic bases other than ammonia remain in the coating film and are not preferable because they tend to deteriorate water resistance and the like.

Specific examples of the volatile amines include monomethyl amine, dimethylamine, trimethyl amine, monoethyl amine, diethyl amine, triethyl amine, monopropyl amine, dimethyl propyl amine, mono ethanol amine, diethanol amine and triethanol amine. 1 selected from N-methyl ethanol amine, N-amino ethyl ethanol amine, N-methyl diethanol amine, mono isopropanol amine, diisopropanol amine, triisopropanol amine or various amines represented by N, N-dimethyl propanol amine, etc. Species or two or more kinds.

At the time of water solubilization, a part or all of the carboxyl groups in the reaction product may be neutralized as a basic substance and then dispersed in water.

As a method for dispersing the heavy product of the reaction product in water, water may be added dropwise while stirring the neutralized product, and the reaction product may be added dropwise to the well stirred water.

Alternatively, a method of dispersing in water while providing mechanical shearing force by a homogenizer, colloid mill, static mixer, or ring can be employed. Alternatively, a method of using ultrasonic waves when dispersing in water is also preferable.

In this way, the water-soluble vinyl-modified epoxy ester resin which is an essential component in the water-soluble resin composition used by this invention can be manufactured.

As a water-soluble resin composition used by this invention, in addition to a water-soluble vinyl modified epoxy ester resin, the hardening | curing agent used for hardening a water-soluble vinyl modified epoxy ester resin as needed; And / or powder or colloid (sol) of a specific metal oxide for improving corrosion resistance may be used in combination.

Among them, the use of the curing agent is particularly effective in improving solvent resistance and alkali resistance.

Specific examples of the hardeners that can be used include amino resins, blocked isocyanate compounds, desiccants, epoxy compounds, and aziridine compounds. Although there is no restriction | limiting in particular as these types, Among these, the use of the amino resin, blocking isocyanate compound, desiccant, etc. which have favorable storage stability in the water-soluble medium with the vinyl-modified epoxy ester resin mentioned above is common.

Illustrative examples of the amino resins are exemplified by "Super Beckermin J-820-60, G-821-60 or L-128-60" [trade name; product of Dainippon Ink & Chemicals Co., Ltd.]. Various butyl etherated melamine resins; Or various butyl ether urea resins such as `` Bacamine G-1850 or P-196-60 '' (trade name; product of Dainippon Ink & Chemicals Co., Ltd.); Or 325 " [trade name; manufactured by Mitsui Cyctic Co., Ltd.] and the like, and various methyl etherated melamine resins; and the like, and various commercial products can be used as they are.

Particularly representative examples of the blocked isocyanate compound are exemplified, regardless of the difference between the water-soluble blocked isocyanate compound and the water-insoluble blocked isocyanate compound. However, when the water-insoluble blocked isocyanate compound is used, the blocked isocyanate compound is added to the paint immediately before use and is forcibly If it is used while stirring, since stability may worsen and it may settle, the use of a water-soluble blocked isocyanate compound is preferable at that point.

Blocking isocyanate compounds which can be used are exemplified by the representative examples of the blocking isocyanate compounds. Examples of the blocking agent for the isocyanate group include various alcohols such as methanol, ethanol, n-propanol, iso-propanol, n-butanol or iso-butanol; Various phenols represented by phenol, cresol, nitro phenol, crorophenol or resorcinol; Various thiocols represented by benzene thiol and the like; various caprolactams represented by ε-caprolactam and the like; Various carbamates represented by ethyl carbamate and the like; Various ketoenols represented by acetyl acetone and the like; Various ketoximes represented by methyl ethyl ketoxime and the like; Or various blocking agents (blocking agents) such as sodium bisulfite (sodium bisulfite), etc. Representative various isocyanate compounds or their prepolymers are reacted at a temperature of about 30 ° C. to about 100 ° C. in the absence of a catalyst or in the presence of a catalyst such as dibutyltin dilaurylate, and the like in which isocyanate groups are blocked. The same type can be used.

Moreover, when only the typical thing is illustrated as said drying agent which can be used, Various aliphatic carboxylic acid represented by olefinic acid etc .; Anionic emulsifiers on various metal soaps represented by cobalt salt, manganese salt, zirconium salt, calcium salt, iron salt or lead salt, etc., supported by various alicyclic carboxylic acids such as naphthenic acid, or the like , A cationic emulsifier or a nonionic emulsifier is added, and water solubilization is added. These may be used alone or in combination of two or more.

The amount of these metal soaps and their water-soluble hydrates is in the range of about 0.003 to 0.5% by weight as the metal powder, and when the added amount is less than 0.003% by weight, the effect is hardly recognized. In the case of using a large amount, there is a drawback that the water resistance is worse than anything else, and therefore it is not preferable in any case, and the preferred amount is preferably in the range of 0.05 to 0.4% by weight as a metal powder.

In addition, as a hardening | curing agent, various tertiary amine etc. which are represented by dimethyl aniline, diethyl aniline, dimethyl paratoluidine, etc. are mentioned.

Except for the drying agent, the amount of the curing agent used is in the range of about 1 part by weight to about 50 parts by weight based on 100 parts by weight of the water-soluble vinyl-modified epoxy ester resin in terms of solid content of the water-soluble vinyl-modified epoxy ester resin. Since it is suitable, the quantity within such a range may be used.

Particularly representative examples of powders or colloids (sols) of metal oxides include SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, having particle diameters of 1 to 15 nanometers (nm), ZrO ₂ , SnO ₂ , Al ₂ O _3, Sb ₂ O ₅ , powders or colloids (sols) and the like, and one or two or more kinds thereof can be exemplified.

The amount of the metal oxide powder or the colloid (sol) is suitably in the range of about 10 parts by weight to about 100 parts by weight based on 100 parts by weight of the resin in terms of solid content of the water-soluble vinyl-modified epoxy ester resin. You can use

By adding a colloidal substance of a metal oxide, it is possible to obtain an organic composite-plated steel sheet with remarkably improved corrosion resistance and the like, without deteriorating the sensibility after coating or coating.

In the present invention, preferably used as a resin composition for coating for chromate-coated alloy plated steel sheet, an epoxy ester resin obtained by the reaction of an aromatic epoxy resin with a fatty acid is a vinyl having a carboxyl group-containing ethylenic vinyl monomer as an essential component. 100 parts by weight of the solid content of the water-soluble vinyl-modified epoxy ester resin (A-1) obtained by modification by addition reaction of the monomer and neutralized with a basic compound, SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , About 10 parts by weight to about 100 parts by weight of one or two or more kinds of powders or colloids (B) of Fe ₃ O ₄ , MgO, ZrO ₂ , SnO ₂ , Al ₂ O _3, or Sb ₂ O ₅ , and a curing agent What is necessary is just to use the thing of the form which consists of about 1 weight part-about 50 weight part of (C), and 0 to about 50 weight part of pigments (D) as needed.

In addition, the present invention is a water-soluble resin obtained by uniformly mixing the water-soluble vinyl-modified epoxy ester resin, the vinyl-modified epoxy ester resin as described below, and the blocked isocyanate compound at the molecular level, and then water-soluble instead of the curing agent. In the case of using the composition, an organic composite plated steel sheet excellent in corrosion resistance can be obtained.

A water-soluble resin composition containing a water-soluble vinyl-modified epoxy ester resin in which a blocked isocyanate compound having excellent corrosion resistance is uniformly mixed at a molecular level is obtained by preparing as follows.

That is, first, the aromatic epoxy resin and the fatty acid are esterified at a temperature of about 150 to 250 ° C. for 2 to 10 hours while heating and stirring, and then dissolved in a desired organic solvent, and then polymerized to a vinyl monomer having a carboxyl group-containing ethylenic vinyl monomer as an essential component. An initiator is added and the mixture is heated and stirred at about 50 ° C to about 150 ° C to perform a graft reaction to obtain a vinyl-modified epoxy ester resin that is a reaction product.

Next, the carboxyl group in this vinyl-modified epoxy ester resin is neutralized with a basic compound, and the blocked isocyanate compound is mixed.

Then, by dispersing in water, a water-soluble resin composition containing a water-soluble vinyl-modified epoxy ester resin in which the desired blocked isocyanate compound is uniformly mixed at the molecular level is obtained.

Herein, the operation of uniformly mixing at the molecular level means that the mixing operation of the neutralized product of the reaction product and the blocked isocyanate compound is carried out through a series of steps of organic or non-solvent type, followed by water oxidation. do.

That is, it is necessary to neutralize a part or all of the carboxyl groups in the reaction product with a basic material prior to the water solubilization, and then mix the blocked isocyanate compound.

Through such a process, it is possible to uniformly mix at the molecular level, thereby obtaining a water-soluble resin composition in which the vinyl-modified epoxy ester resin and the blocked isocyanate compound coexist in the dispersed particles.

As a method for dispersing the neutralized product of the reaction product in water, as described above, the neutralized product may be added dropwise while stirring the neutralized product, or the reaction product may be added dropwise to the well stirred water.

Alternatively, a method of dispersing in water while giving a mechanical shear force or using ultrasonic waves may be similarly employed.

Thus, a water-soluble resin composition containing a water-soluble vinyl-modified epoxy ester resin in which the blocked isocyanate compound, which is an essential component in the water-soluble resin composition, which is particularly excellent in corrosion resistance and the like used in the present invention, is uniformly mixed at a molecular level can be produced. .

In particular, the water-soluble resin composition having excellent corrosion resistance and the like, which is used in the present invention, in addition to the water-soluble vinyl-modified epoxy ester resin in which the blocked isocyanate compound is uniformly mixed at the molecular level, the water-soluble vinyl-modified epoxy ester resin may be further added as necessary. Curing agents for curing; And / or powders or colloids (sols) of specific metal oxides for improving corrosion resistance may be used in combination.

As resin compositions for coating for chromate-coated alloy plated steel sheets excellent in corrosion resistance, which can be preferably used in the present invention, epoxy ester resins obtained by the reaction of aromatic epoxy resins and fatty acids, respectively, include carboxyl group-containing ethylenic vinyl monomers as essential components. A water-soluble vinyl-modified epoxy ester resin (A-2) containing a blocked isocyanate compound obtained by homogeneously mixing and modifying a vinyl-modified epoxy ester resin and a blocked isocyanate compound at a molecular level by modification of an addition reaction of a vinyl monomer. ), And powder or colloid (sol) of SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, ZrO ₂ , SnO ₂ , Al ₂ O ₃ or Sb ₂ O ₅ About 10 parts by weight to about 100 parts by weight of one or two or more kinds, 0 to about 50 parts by weight of the curing agent (C), and 0 to about 50 parts by weight of the pigments (D), if necessary It can be used in the form of a wealth.

Thus, the water-soluble resin composition used in the present invention can be obtained. The organic coating amount of the water-soluble resin composition in the organic composite plated steel sheet according to the present invention is about 0.2 g / m ² to 3.0 g / m ² . It is suitable in range. When the organic coating amount is less than 0.2g / m ^2, it may be difficult to secure the corrosion resistance after processing. On the other hand, when the amount exceeds 3.Og / m ² , the electrodeposition property may be lowered. In addition, it is because it is impossible to secure an electrodeposition coating film having excellent sensibility and the like.

In the water-soluble resin composition, a silane coupling agent for imparting adhesion, such as a plasticizer, an emulsion or styrene butadiene-based latex, other water-soluble resins, etc., as necessary, in addition to the pigment or the water-soluble pigment composition, or in addition to the above-described ingredients. Various conventional well-known additives used for paint, such as these, etc. can be mix | blended.

In carrying out the present invention, the water-soluble resin composition may be coated by any method, such as immersion coating, shower coating, electrodeposition coating, brush coating, spray coating or roll coating, and heat curing after coating. .

Preferably, the desired organic composite plated steel sheet can be obtained by heat curing at a temperature of about 100 ° C. or higher for an arbitrary time.

The organic composite plated steel sheet according to the present invention exhibits a very excellent effect as an organic composite plated steel sheet suitable for use in steel sheets for automobiles, in particular by carrying out subsequent electrodeposition coating.

The organic composite plated steel sheet obtained in the present invention is excellent in adhesiveness with adhesives, continuous welding properties, corrosion resistance after processing and electrodeposition coating properties, and excellent in coating adhesion and corrosion resistance, and especially in the sensibility (smoothness) of drawings after electrodeposition coating. In addition, when the blocked isocyanate compound and the water-soluble resin composition in which the vinyl-modified epoxy ester resin is uniformly mixed at the molecular level are used, the corrosion resistance is excellent.

Next, a description will be given of a method for evaluating the main characteristics of the organic composite plated steel sheet obtained in the present invention.

In other words, first, the evaluation method of the lightness and paint adhesion was subjected to electrodeposition coating using a commercially available electrodeposition paint so as to be 20 microns (μm), and aged at 175 ° C. to evaluate the lightness.

Sensitivity was determined by measuring the PGD of the electrodeposition coating. Evaluation indicators are as shown in the first table.

Paint adhesion is 40 microns (μm) each with a melamine-alkyd resin paint after electrodeposition coating, followed by medium coating and top coating, and drawing in accordance with JIS K-5400.Erichsen Test It was.

In addition, the evaluation was similarly evaluated for the sample after immersing in hot water at 50 ° C. for 240 hours after coating. That is, this is called paint adhesiveness after a hot water test. The evaluation indexes of these paint adhesiveness are as shown in the second table.

The peeling corrosion resistance after processing was evaluated by evaluation of the corrosion resistance in the processing part by pressing the test piece, but the corrosion resistance was 5% by weight of the salt solution by the salt spray test method according to the JIS Z-2371 standard. And tank temperature were 35 degreeC, and spray pressure was performed on 20 PSI conditions.

The presence or absence of the callout in 5000 hours and the extent of the callout were examined and evaluated based on the occurrence area of the callout, but the evaluation indexes were shown in the third table.

Here, the adhesiveness (adhesiveness) to the adhesive is first performed in accordance with the standards of JIS K-6850 and JIS K-6854 as tensile shear adhesive strength and peel adhesive strength, as shown in Tables 4 and 5, respectively. Evaluation was made based on the same evaluation criteria.

Subsequently, continuous welding is performed under the condition that the pressing force is 250 kgf and the energization time is 0.2 second using the CF type electrode of Cu-Cr. The welding current was obtained by determining the current value during dust generation and welding, and setting it as the appropriate welding current in the range, and performing continuous welding by setting the intermediate value (dust generation current value + welding current value) x 1/2) of this suitability welding current as the welding current value. .

In addition, the nugget diameter was measured every 100 RBIs, and the RBI until such a nugget diameter became 5 mm was evaluated by the evaluation index shown in a 6th table | surface.

In addition, corrosion resistance was immersed in a 50% aqueous 5% sodium chloride aqueous solution at 50 ° C. for 15 minutes and dried for 15 minutes in one cycle, and the corrosion resistance at the time when this operation was repeated 200 cycles was observed. Evaluation was made visually, and evaluation was made by evaluation indexes as shown in Table 7.

EXAMPLE

Next, the present invention will be described in more detail with reference to examples, examples, and comparative examples, but the present invention is not limited to these examples unless departing from the technical idea. In addition, all parts and% were weight basis unless there is particular notice.

Reference Example 1

[Preparation Example of Water-Soluble Vinyl-Modified Epoxy Ester Resin (A-1)]

60 parts of dehydrated cauliflower oil, 60 parts of soybean oil fatty acid, 30 parts of safflower oil fatty acid, `` Epiclon 1050 '' under the aeration of nitrogen gas in a clean reaction vessel equipped with a temperature control device and a stirrer (trade name; Dainippon Ink Chemical Co., Ltd.) 225 parts of Kaisha) and 0.2 parts of dimethyl benzylamine were added, and the reaction mixture was heated up to 180 ° C. for 1 hour, and then heated up to 230 ° C. until the acid value became 10.

Subsequently, it cooled to 100 degreeC, added 250 parts of butyl cellosolves, and stirred well, it heated up to 120 degreeC, over 50 hours, 50 parts of methacrylic acid, 33 parts of acrylic acid, and 25 parts of 2-hydroxy ethyl acrylate. And 25 parts of 2-hydroxy ethyl methacrylate and 25 parts of tert butyl peroxides were dripped, and it maintained for 4 hours as it is.

After cooling to 50 ° C., 110 parts of triethylamine were added and stirred well, and 440 parts of ion-exchanged water was added dropwise to obtain a milky white target resin solution having a nonvolatile content of 40%. Hereinafter, this is abbreviated as resin (4-1-1).

The resin (A-1-1) has an aromatic epoxy resin and a fatty acid in a ratio of 60:40 (parts by weight: the same below), and the amount of the total ethylenic vinyl monomer and the carboxyl group-containing ethylenic vinyl monomer is used in the aromatic epoxy resin. For 100 parts of the reaction product of the fatty acid were 35.5 parts and 22.1 parts, respectively.

Reference Example 2 [Same]

In a clean reaction vessel equipped with a temperature control device and a stirrer, 75 parts of dehydrated main fatty acid fatty acid, 75 parts of soybean oil fatty acid, 75 parts of safflower oil fatty acid, 150 parts of `` Epiclon 1050 '' and 0.2 parts of dimethyl benzylamine were added under aeration of nitrogen gas. The reaction mixture was heated up to 1 ° C. for 1 hour, and then heated up to 230 ° C. until the acid value became 5.

Thereafter, the mixture was cooled to 100 ° C, 250 parts of butyl cellosolve was added, and the temperature was raised to 120 ° C while stirring well. There were 50 parts of acrylic acid, 25 parts of 2-hydroxyethyl acrylate and 25 parts of styrene, and tert there over 4 hours. 20 parts of -butyl peroxides were dripped, and it maintained for 4 hours as it is.

After cooling to 50 ° C., 60 parts of triethylamine were added and 417.5 parts of ion-exchanged water was added dropwise while stirring well to obtain a milky white target resin solution having a nonvolatile content of 40%. Hereinafter, this is abbreviated as resin (A-1-2).

The resin (A-1-2) had an aromatic epoxy resin and fatty acid ratio of 40:60, and the total amount of the ethylenic vinyl monomer and the carboxyl group-containing ethylenic vinyl monomer was used in 100 parts of the aromatic epoxy resin and the fatty acid reaction product. 24 parts and 10.5 parts respectively.

Reference Example 3

[Preparation Example of Water-Soluble Vinyl-Modified Epoxy Ester Resin (A-2)]

In a clean reaction vessel equipped with a temperature controller and a stirrer, under aeration of nitrogen gas, 60 parts of dehydrated main fatty acid, 60 parts of soybean oil fatty acid, 30 parts of Hunghwa oil fatty acid, 225 parts of Epiclone 1050, and 0.2 part of dimethyl benzylamine The mixture was heated to 180 ° C. and reacted for 1 hour, and then heated up to 230 ° C. until the acid value became 10.

Subsequently, it cooled to 100 degreeC, added 250 parts of butyl cellosolves, and heated up to 120 degreeC, stirring well, and thereafter 50 parts of acrylic acid, 25 parts of 2-hydroxy ethyl acrylate, and tert-butyl peroxide 10 over 4 hours. Wealth was dropped and kept for 4 hours.

77 parts of triethylamines were added after cooling to 50 degreeC, and it stirred well. Subsequently, 30 parts of hexamethylene diisocyanate, methylethyl ketoxime, blockide as a fluorinated isocyanate compound were added and mixed well for 30 minutes.

Thereafter, 408 parts of ion-exchanged water was added dropwise while stirring, whereby a target resin solution containing a milky white blocked isocyanate compound having a nonvolatile content of 40% and a vinyl-modified epoxy ester resin at a molecular level was obtained. Hereinafter, this is abbreviated as resin (A-2-1).

The resin (A-2-1) has an aromatic epoxy resin and fatty acid ratio of 60:40, and the total amount of the ethylenic vinyl monomer and the carboxyl group-containing ethylenic vinyl mono is 100 parts of the aromatic epoxy resin and the fatty acid reaction product. 20 parts and 13.3 parts respectively. Moreover, the content rate of the blocked isocyanate compound was 6% in solid content of the said resin (A-2-1).

[Examples 1-9 and Comparative Examples 1-5]

Each resin liquid obtained in Reference Examples 1 to 3 was blended in a formulation (as described in the solid content ratio) as shown in Table 8 to prepare resin compositions for paints for various chromate coated alloy plated steel sheets.

In addition, A in the resin type column in Table 8 represents resin (A-1-1) obtained in Reference Example 1, B represents resin (A-1-2) obtained in Reference Example 2, and C is Reference Example 3 Resin (A-2-1) obtained in the following is shown.

Moreover, commercially available carboxylated polyethylene emulsion (X) and aromatic epoxy emulsion (Y) were used as a control product for comparative examples. Moreover, as a hardening | curing agent, the thing ((alpha)) of the form which was hydrated with hexamethylene diisocyanate methyl ethyl ketoxim block, the nonionic dispersing agent (alpha), diphenylmethane diisocyanate methyl ethyl ketoxim block, (Β) and "CYMEL 303" (brand name: Mitsui Cyctic Co., Ltd. product) ((gamma)) of the form made into water using the nonionic dispersing agent were used.

In addition, as the metal oxide powder or colloid (sol), respectively, water dispersion (M1) of SiO having an average particle diameter of 10 nm, water dispersion (M2) of CrO having an average particle diameter of 8 nm, and an average particle diameter of 6 nm, respectively. AlO (M3) was used.

As the pigment, an aqueous pigment (manufactured by Dainippon Ink Chemical Co., Ltd.) of a form obtained by dispersing an azoleki pigment with a nonionic dispersant was used.

Next, the chromate coatings described in the tables were coated on the coated steel sheets having the adhesion amounts and plating compositions as shown in Table 9, respectively, and the coating resin composition for the chromate coated alloy coated steel sheets was applied and dried at 150 ° C. for 15 seconds. Cured. The evaluation results of the organic composite plated steel sheet thus obtained are also shown in the same table.

As described above, the organic composite plated steel sheet obtained in the present invention is excellent in adhesiveness, continuous welding property, corrosion resistance after processing, and electrodeposition coating property, and also excellent in paint adhesion and corrosion resistance, and especially on the coated surface after electrodeposition coating (smoothness) ), And the water-soluble resin composition in which the blocked isocyanate compound and the vinyl-modified epoxy ester resin are uniformly mixed at the molecular level provides excellent corrosion resistance, and is particularly suitable for use in automotive steel sheets and the like by applying subsequent electrodeposition coatings. As an organic composite plated steel sheet, it exhibits a very excellent effect.

Claims (10)

In the organic composite plated steel sheet obtained by applying and curing a thermosetting resin on a chromate-coated alloy plated steel sheet, the epoxy ester resin obtained by the reaction of an aromatic epoxy resin and a fatty acid as the thermosetting resin is a carboxyl group-containing ethylenic vinyl monomer. An improved organic composite plated steel sheet comprising a water-soluble resin composition containing a water-soluble vinyl-modified epoxy ester resin obtained as an essential film-forming component obtained by modification by addition reaction of a vinyl monomer as a component and neutralization with a basic compound. In the organic composite plated steel sheet obtained by coating and curing a thermosetting resin on a chromate-coated alloy plated steel sheet, the epoxy ester resin obtained by the reaction of an aromatic epoxy resin and a fatty acid as the above-mentioned thermosetting resin includes a carboxyl group-containing ethylenic vinyl monomer. An improved organic composite plated steel sheet comprising a water-soluble vinyl-modified epoxy ester resin obtained by modification by addition reaction of a vinyl monomer to be neutralized with a basic compound and a water-soluble resin composition comprising the curing agent. In the organic composite plated steel sheet obtained by applying and curing a thermosetting resin on a chromate coated alloy coated steel sheet, the epoxy ester resin obtained by the reaction of an aromatic epoxy resin with a fatty acid as the thermosetting resin is a carboxyl group-containing ethylenic vinyl monoter as an essential component. A water-soluble vinyl-modified epoxy ester resin obtained by modification by addition reaction of a vinyl monomer to be neutralized with a basic compound, SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, ZrO ₂ , SnO An improved organic composite plated steel sheet comprising a water-soluble resin composition comprising ₂ , Al ₂ O ₃ or Sb ₂ O ₅ powders or colloids (sols). In the organic composite plated steel sheet obtained by applying and curing a thermosetting resin on a chromate-coated alloy plated steel sheet, the above-mentioned thermosetting resin is an epoxy ester resin obtained by the reaction of an aromatic epoxy resin with a fatty acid and a carboxyl group-containing ethylenic vinyl monomer. A water-soluble vinyl-modified epoxy ester resin obtained by modification by addition reaction of a vinyl monomer to be neutralized with a basic compound, a curing agent thereof, SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, An improved organic composite plated steel sheet comprising a water-soluble resin composition comprising one or two or more powders of ZrO ₂ , SnO ₂ , Al ₂ O _3, or Sb ₂ O ₅ , or a colloid (sol). The improvement according to claim 2 or 4, wherein the water-soluble vinyl-modified epoxy ester resin and its curing agent are obtained by uniformly mixing and water-soluble vinyl-modified epoxy ester resin and a blocked isocyanate compound at a molecular level. Organic composite plated steel sheets. The organic composite plating steel sheet obtained by apply | coating and hardening the said water-soluble resin composition in any one of Claims 1-4 is 0.2-3.0 g / m <^2> . The vinyl-modified epoxy ester resin and the blocked isocyanate compound are homogeneously mixed at the molecular level according to claim 5, prior to modification by addition reaction of the vinyl monomer to the epoxy ester resin according to claim 2, An improved organic composite plated steel sheet, characterized in that the amount of the organic coating obtained by applying and curing the water-soluble resin composition obtained by the aqueous phase is 0.2 to 3.0 g / m ² . The vinyl-modified epoxy ester resin and the blocked isocyanate compound are homogeneously mixed at the molecular level in advance of modification by the addition reaction of the vinyl monomer to the epoxy ester resin according to claim 4, followed by aqueous phase formation. An improved organic composite plated steel sheet, characterized in that the amount of the organic coating obtained by applying and curing the water-soluble resin composition obtained by the treatment is 0.2 to 3.0 g / m ² . A water-soluble vinyl-modified epoxy ester resin obtained by modifying an epoxy ester resin obtained by the reaction of an aromatic epoxy resin with a fatty acid by addition reaction of a vinyl monomer having a carboxyl group-containing ethylenic vinyl monomer as an essential component and neutralizing with a basic compound (A- 1) and powder of colloidal (sol) (B) of SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, ZrO ₂ , SnO ₂ , Al ₂ O ₃ or Sb ₂ O ₅ The resin composition for coating materials for chromate-coated alloy plated steel sheets containing species or two or more types, a hardening | curing agent (C), and pigments (D) as needed. Epoxy ester resin obtained by the reaction of aromatic epoxy resin and fatty acid is uniformly modified at the molecular level of vinyl-modified epoxy ester resin and blocked isocyanate compound by addition reaction of vinyl monomer having carboxyl group-containing ethylenic vinyl monomer as an essential component. Water-soluble vinyl-modified epoxy ester resin (A-2) containing a blocked isocyanate compound obtained by mixing and solubilizing, SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, ZrO ₂ , SnO ₂ , One or two or more kinds of powders of Al ₂ O ₃ or Sb ₂ O ₅ or colloid (sol) (B), a curing agent (C) if necessary, and pigments (D) as necessary. A resin composition for coating for chromate-coated alloy plated steel sheet.